If you want to really be good at identifying fakers, the best thing you can do is to be a faker yourself and no it's not something that you can learn for a month, you should be a faker ever since because there are nuances to emotions and facial movement and only fakers can identify other fakers. It's hard to identify fake emotions especially if you're a genuinely nice person that wants to believe that there's good in everyone plus there are other people that aren't really good with expressing what they're feeling so the way they deliver their reaction is kind of awkward that we will think that it's a fake one and that's why I believe that it's easier if you are a faker yourself to be able to identify fake laughs and fake reactions. That's not the rule though as common sense is a thing, there are others that don't bother hiding that they're faking.

The answer to your question regarding these casino streamers being popular is that they're all famous people that have influence on a variety of people that are watching their streams plus they're a cheaper way for casinos to hire to advertise their business and they get a ton of value out of it because streamers have a live audiences and that's the wet dream of any advertiser, a live audience that they can bombard with ads without the audiences being annoyed of it because they're favorite streamers are playing it, factor the fact that most famous streamers are bombastic and always interacting with their audiences which helps maintain attention span and more exposure for the casino advertisement.